Charles was tutored by M. le Masson, a canon of Soissons, and displayed a remarkable memory even at a young age.
His father was still determined that Charles should join the army either at Calais or in Holland, but perceiving the serious of the illness, agreed that should his son recover, he could enter religious life.
He gave up his family inheritance, which by the law of primogeniture was his, and entered the house of the French Oratory founded by the Abbé (later Cardinal) Pierre de Bérulle on the Rue Saint-Honoré in Paris, having thought before that of becoming a Capuchin friar.
In 1615, Condren participated in the foundation of a new house of the Oratory in Nevers and in 1619 was in Langres for the opening of a seminary, in conformity to the decrees of the Council of Trent.
The Catholic Church felt that its success in its own renewal lay in the thorough and systematic formation of the clergy through their education in these schools.
A disciple of both Vincent de Paul, and Condren, Jean-Jacques Olier took part in "missions" organized by them in France.